Hello dear, PRILOSEC is pharmacologically Omeprazole, a proton pump inhibitor, which prevents the formation of acid in stomach. This excess acid formation is the main cause for ulcer formation in the duodenum. So, the medicine given by your doctor is correct. Side effects of Omeprazole includes headache, diarrhea, abdominal pain, nausea, dizziness, etc. but they are usually very mild & are well tolerated. So, you can try the medications for 2 more days, if the sensation of dizziness & blurring of vision still persist, kindly consult your treating physician & discuss about changing the medicines. Also get your blood pressure & blood sugar levels checked, as any fluctuations in their parameters can also cause such symptoms. Hope this helps. Please let me know if I need to clarify further. Wishing you a Good Health. Take care.